The International Society of Experimental Hematology (ISEH) was established over 20 years ago by young - then - hematology researchers whose principal interest was in hematopoietic stem cells, their growth factors and bone marrow transplantation. Its conferences are of special importance to the careers of many young investigators, not only because stem cells, growth factors and bone marrow transplantation are exciting and promising research areas but, also, because of the relatively small size of the meetings, conferees have ample opportunities for social interaction and networking with colleagues. The 21st Annual Meeting of the International Society of Experimental Hematology will be hosted in Providence, Rhode Island on July 26-30, 1992. A distinguished Scientific Committee has been assembled which will plan a scientific program different from those of other hematological conferences during this coming year and which will also contain significant new information. Themes of the plenary sessions by the Scientific Committee include: 1. Gene expression during hematopoietic cell differentiation; 2. Synergistic interactions between growth factors (a) in vitro, (b) in vivo - preclinical, clinical; 3. Apoptosis: (c) preclinical/clinical studies; 5. Cytokine interactions; 6. Stromal regulation of hematopoiesis; 7. Membrane-bound regulators of hematopoiesis, 8. Stem cell tracking (after transplantation). The Scientific Committee will have, in addition, the responsibility of selecting among all the submitted abstracts the most worthwhile for brief oral presentations and will advise us on the expenditure of funds to cover travel expenses for invited speakers as well as for promising young investigators. Finally, in keeping with the long interest of ISEH in the fostering of the research careers of young investigators, we are arranging to have technical workshops in laboratory research methodologies on the Brown University campus on the weekend preceding the conference at no additional registration cost to the participants and with much reduced housing fees.